Printing head feeding mechanism for printers

ABSTRACT

A printing head feeding mechanism for printers comprising a pair of pulleys respectively arranged at positions near both limits of the moving range of a printing head, an intermediate pulley rotatably supported at an end of crank lever and movable between said pair of pulleys, and a rope connected to said printing head and applied between said pair of pulleys after which both sides of said rope are respectively applied in S-shape between said intermediate pulley and each of said pair of pulleys and both ends of said rope are held in fixed condition, in order to enable said printing head reciprocate in a comparatively long linear distance when said crank lever is reciprocated in a range of comparatively small angle.

1451 May 27, 1975 PRINTING HEAD FEEDING MECHANISM FOR PRINTERS [75] Inventor: Katsuhiko Okabe,Tokorozawa,

Japan [73] Assignee: Kabushiki Kaisha Koparu,

Tokyo-to, Japan [22] Filed: Oct. 15, 1973 [21] Appl. No.: 406,339

[30] Foreign Application Priority Data 3,352,398 11/1967 Crutcher et al. 197/16 3,581,360 6/1971 Schaefer 197/16 X 3,677,384 7/1972 Link 197/16 Primary ExaminerEdgar S. Burr Assistant Examiner-R. T. Rader Attorney, Agent, or FirmCushman, Darby & Cushman [5 7] ABSTRACT A printing head feeding mechanism for printers comprising a pair of pulleys respectively arranged at positions near both limits of the moving range of a printing head, an intermediate pulley rotatably supported at an end of crank lever and movable between said pair of pulleys, and a rope connected to said printing head and applied between said pair of pulleys after which both sides of said rope are respectively applied in S- shape between said intermediate pulley and each of said pair of pulleys and both ends of said rope are held in fixed condition, in order to enable said printing head reciprocate in a comparatively long linear distance when said crank lever is reciprocated in a range of comparatively small angle.

2 Claims, 2 Drawing Figures PRINTING HEAD FEEDING MECHANISM FOR PRINTERS BACKGROUND OF THE INVENTION a. Field of the invention:

The present invention relates to a printer for printing with reciprocating motion of a printing head and, more particularly, to a printing head feeding mechanism in said type of printer.

b. Description of the prior art:

The coventional printing head feeding mechanism used for printers of the said type comprises a cam rotated by a motor, a crank lever which finishes one reciprocating motion by one rotation of said cam and a printing head directly or indirectly mounted on one arm of said crank lever. In case of the feeding mechanism of said arrangement, the crank lever has to be swung by the amount corresponding to the travelling stroke of the printing head. Therefore, the cam and lever have to be large and, consequently, the printer as a whole becomes large.

SUMMARY OF THE INVENTION It is, therefore, the primary object of the present invention to provide a printing head feeding mechanism arranged so that the printing head can be moved about twice the movement of the crank lever in order to eliminate the disadvantage of said conventional feeding mechanism.

This object can be attained, according to the present invention, by arranging the feeding mechanism by a pair of pulleys respectively arranged at positions near both extreme limits of the moving range of the printing head, an intermediate pulley rotatably supported at one end of the crank lever so that said pulley can be moved between said pair of pulleys and a rope connected to the printing head at one portion, applied between said pair of pulleys and then applied between said intermediate pulley and each one of said pair of pulleys respectively in S-shape and, then, both ends of said rope being held in fixed condition.

Other objects as well as the attendant advantages of the present invention will become apparent from the following detailed description of the preferred embodiment when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a perspective view of the important part of the printing head feeding mechanism according to the present invention; and

FIG. 2 shows an explanatory diagram illustrating the relationship of the mount of movement of the printing head to the movement of the intermediate pulley.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, reference numeral 1 designates a motor, numeral 2 designates a driving gear rotated by the motor 1, and numeral 3 designates an intermediate gear meshing with the driving gear 3. Numeral 4 designates a toothed wheel having square teeth 4a, on its circumference, for generating position signals for controlling the horizontal feed of the platen which is not illustrated here. The toothed wheel 4 rotates integrally with the intermediate gear 3. Numeral 5 designates an intermediate pinion which rotates integrally with the intermediate gear 3. Numeral 6 designates a position signal detecting coil arranged opposite to face a square tooth 4a of the toothed wheel 4. Numeral 7 designates an operating gear which meshes with the intermediate pinion 5. Numeral 8 designates a cam member which forms a groove cam 8a and is provided on the operating gear 7 at a position eccentric to the axis of rotation of the operating gear 7. Numeral 9 designates a crank lever pivotably mounted on a shaft 10 to which a pin 9a for fitting in the groove cam 8a is fixed to one arm and a supporting shaft 9b is fixed to the other arm. Numeral 11 designates an intermediate pulley rotatably mounted on the supporting shaft 9b. Numeral 12 designates a pair of pulleys rotatably mounted respectively on shafts 12a arranged near both ends of the moving range of the printing head. Numeral 13 designates a rope which is first applied between pulleys l2 and 12 so that the rope is stretched between those pulleys. Then, both sides of the rope 13 are applied in S-shape between the intermediate pulley 11 and respective ones of pulleys 12 and 12. After that, both ends of the rope 13 are held in fixed condition. Numeral 14 designates a pair of levers for supporting a rail 16 which are pivotably mounted on shafts 15 and 15, respectively. Numeral l7 designates a head holder which is connected to the rope 13 by a connecting piece 17a and, at the same time, is mounted on the rail 16 by a pair of protuberances 17b and 17b so that the head holder 17 can move along the rail 16. Numeral 18 designates a printing head secured to the head holder 17. The printing head 18 faces a platen which is not shown here.

This feeding mechanism is arranged to suit a heatsensing type electronic printer. The motor 1 rotates only when printing and stops when the operating gear 7 finishes one rotation. During said one rotation of the operating gear 7, the printing head 18 finishes its one reciprocating motion between pulleys l2 and 12, thus printing of one line is carried out.

That is, this printer is arranged so that a stop signal for the motor 1 is generated when the operating gear 7 finishes one rotation. When the operating gear 7 finishes one rotation, the crank lever 9 also finishes its one reciprocating motion by means of the cam member 8 and the pulley ll rotatably mounted on the shaft 9b of the crank lever 9 also finishes, by rotating, its one reciprocating motion almost in parallel with the line connecting pulleys l2 and 12. As a result, the head holder 17 connected to the rope l3 reciprocates along the rail 16 and the printing head 18 also reciprocates along the platen.

In this case, the relation of movement of the pulley l1 rotatably mounted on the supporting shaft 9b of the crank lever 9 and movement of the rope 13 to which the head holder 17 is connected is as shown in FIG. 2. From this figure, it will be understood that the head holder 17, i.e., the printing head 18 moves twice (2A) the amount of movement (A) of the pulley 11 provided that the pulley 11 moves accurately in parallel with the I rope 13 applied between pulleys 12 and 12.

Actually, the intermediate pulley 11 moves in a circular are around the shaft 10. Therefore, the amount of movement of the printing head 18 is not accurately twice the amount of movement of the intermediate pulley 11 and the amount of movement of the printing head 18 is not in direct proportion to the amount of movement of the intermediate pulley 1 1. But, these can be compensated by making the distance between the shaft and supporting shaft 9b as long as possible and by selecting the shape of the groove cam 8a of the cam member 8 in a suitable form.

In practice, the advancing movement of the printing head 18 is utilized for printing operation and the returning movement is utilized for returning operation to the starting position. Therefore, in the advancing movement, it is necessary to push the printing head 18 against the platen. FIG. 1 shows an example of said mechanism. That is, on the bottom side of the operating gear 7, a cylindrical cam member 7a is formed so that a half circle of which has a different height from the other half. On the other hand, a roller 20a is rotatably mounted on a shaft 20 which is fixed to a lever 19, said lever being connected to the supporting lever 14 by a pinand-slot connection and being rotatably supported by a shaft 19a so that the lever 19 intersects with the supporting lever 14. This roller 20a is arranged to contact the cam surface of the cam member 7a. That is, during the 180 turn for the first half of the rotation of the operating gear 7, the roller 20a contacts the lower portion of the cam surface of the cam member 7a. Besides, through the lever 19 which is turned toward the direction shown by the arrowhead by means of a spring 21, the supporting lever 14 is turned in the direction shown by the arrowhead around the shaft 15 by means of a spring 22. Thus, the printing head 18 is pushed to the platen when the supporting lever 14 is turned in the direction shown by the arrowhead.

Furthermore, the position signal in horizontal direction along the platen is generated in the detecting coil 6 according to the relative position of the aforesaid toothed wheel 4 with square teeth 4a and detecting coil 6. The position signal in vertical direction is given by another element which is not illustrated here. Numerals and letters are formed by combination of signals for both directions.

During the 180 turn for the latter half of the rotation of the operating gear 7, the roller 20a contacts the higher portion of the cam surface of the cam member 7a as shown in FIG. 1. Therefore, the supporting lever 14 is turned in the direction opposite to the arrowhead in order to release the printing head 18 from the platen, thus the printing head 18 is returned to the starting position. At the same time, by rotary motion of the operating gear 7 during this latter 180 turn, the paper to be printed which exists between the printing head 18 and platen is fed though it is not illustrated here.

In the above, the feeding mechanism of the present invention is described referring to an embodiment suitable for an electronic printer of heat-sensingtype. It is evident, however, that the feeding mechanism according to the present invention can be also applied to printers of electric discharge type, ink-jet type and mechanical type. i

I claim:

1. A printing head holder feeding mechanism for printers, comprising: an operating gear, a first cam member formed on said operating gear, a crank lever engaged with said first cam member and arranged to complete one to-and-fro motion by means of one rotation of said operating gear, an intermediate pulley rotatably mounted on one end of said crank lever, a pair of pulleys positioned at both sides of said intermediate having a respective end of said extending portions held in fixed condition, one of said extending portions being shaped in S-shape and the other being shaped in reverse S-shape, a printing head connected to said rope and movable between said pair of pulleys, and a rail slidably supporting said printing head for linear movement of said printing head.

2. A printing head feeding mechanism for printers, comprising: an operating gear, a first cam member formed on said operating gear, a crank lever engaged with said first cam member and arranged to complete one to-and-fro motion by means of one rotation of said operating gear, an intermediate pulley rotatably mounted on one end of said crank lever, a pair of pul leys positioned at both sides of said intermediate pulley leaving a space between each other, a rope applied between said pair of pulleys and also applied in S-shape between said intermediate pulley and each of said pair of pulleys, both ends of said rope being held in fixed condition, a printing head connected to said rope and movable between said pair of pulleys, and a rail slidably supporting said printing head for linear movement of said printing head, a rotatable supporting lever fixed to said rail, a shaft engaged to said supporting lever, a roller rotatably mounted on said shaft, and a second cam member formed on said operating gear and having two different kinds of cam surfaces engageable with said roller, said printing head being held in its printing position only during half a rotation of said operating gear. 

1. A printing head holder feeding mechanism for printers, comprising: an operating gear, a first cam member formed on said operating gear, a crank lever engaged with said first cam member and arranged to complete one to-and-fro motion by means of one rotation of said operating gear, an intermediate pulley rotatably mounted on one end of said crank lever, a pair of pulleys positioned at both sides of said intermediate pulley leaving a space between each other, a printing head holder movable between said pair of pulleys, a rope having an intermediate portion connected to said printing head holder and having extending portions respectively extended from said intermediate portion in the opposite direction and applied between each of said pair of pulleys and said intermediate pulley and further having a respective end of said extending portions held in fixed condition, one of said extending portions being shaped in S-shape and the other being shaped in reverse S-shape, a printing head connected to said rope and movable between said pair of Pulleys, and a rail slidably supporting said printing head for linear movement of said printing head.
 2. A printing head feeding mechanism for printers, comprising: an operating gear, a first cam member formed on said operating gear, a crank lever engaged with said first cam member and arranged to complete one to-and-fro motion by means of one rotation of said operating gear, an intermediate pulley rotatably mounted on one end of said crank lever, a pair of pulleys positioned at both sides of said intermediate pulley leaving a space between each other, a rope applied between said pair of pulleys and also applied in S-shape between said intermediate pulley and each of said pair of pulleys, both ends of said rope being held in fixed condition, a printing head connected to said rope and movable between said pair of pulleys, and a rail slidably supporting said printing head for linear movement of said printing head, a rotatable supporting lever fixed to said rail, a shaft engaged to said supporting lever, a roller rotatably mounted on said shaft, and a second cam member formed on said operating gear and having two different kinds of cam surfaces engageable with said roller, said printing head being held in its printing position only during half a rotation of said operating gear. 